The research will center on the synthesis and single crystal x-ray structural characterization of phosphate substrates and intermediates important in providing an accurate model of the mechanism of action of ribonuclease and staphylococcal nuclease. The compounds chosen will isolate specific enzyme features for study. Included will by cyclic and acyclic phosphate substrates containing PO2, POS, and POR groupings, monophosphate and diphosphate nucleosides, and phosphoranes which model the nuclease transition states. NMR, infrared and laser Raman spectroscopy will provide important information on solution and solid state behavior regarding structural comparisons and the extent of conformation nonrigidity of pentacoordinate derivatives. A variety of departing groups, base functions, and hydrogen bonding possibilities will be explored in the conformational studies to aid in unraveling the intricate interplay of steric and electronic forces guiding enzymatic reactions on phosphorous substrates. Selected reaction rates will be measured. Interpretation of the structural and rate data is expected to provide an intimate understanding of the mechanistic pathways of these nuclease reactions and of the contrasting variations apparent in related nonenzymatic reactions.